Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1992-10-13
1993-12-14
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
257 53, G01J 350
Patent
active
052705366
ABSTRACT:
A method of using measurements of the dc photocurrent produced by a photodetector to determine the wavelength or color of incident light, or to characterize certain properties of a semiconductor device or material. The intrinsic wavelength filtering ability of the photodetector is used as the basis for determining the wavelength of incident light by relating measurements of the dc photocurrent versus reverse bias voltage to the absorption coefficient of the semiconductor material from which the detector is fabricated. Color detection is accomplished by expressing the measured photocurrent as a linear combination of the photocurrents due to detection of each of the three primary colors. The coefficients of each of the terms of the linear combination are then varied to obtain the best fit to the measured photocurrent. This allows a determination of the color of the detected light based on the respective contributions of each of the primary colors to its actual color. The relationship between the absorption coefficient and wavelength can also be used to infer important characteristics of the semiconductor material from which the photodetector is fabricated. In this application of the method, monochromatic light of a known wavelength is used to illuminate the photodetector and measurements of the photocurrent versus reverse bias voltage are used to infer the value of the absorption coefficient corresponding to the wavelength of the light. These measurements can also be used infer the depletion width and doping density of the material.
REFERENCES:
patent: 4749851 (1988-06-01), Wolffenbuttel
patent: 4791396 (1988-12-01), Nishizawa et al.
patent: 5140397 (1992-08-01), Haga et al.
M. Welling & V. Melhotra, "Novel Techniques of Sensing Wavelength and Color of Visible Light", proceedings of Electrochemical Society Meeting, Oct. 13-17, 1991, presented in Phoenix on Oct. 16, 1991, 6 pages in length.
M. Welling & V. Malhotra, "Color Detection Using Amorphous Silicon Schottky Photodiode", Sensors and Actuators A, 29 (1991), publisher: Elsevier Sequoia, Lausanne, 6 pages in length (pp. 195-200).
V. Malhotra & M. Weling, "A Novel Technique for Characterization of Amorphous Silicon Thin Films," Materials Research Society Meeting (Apr. 27-May 1, 1992 in San Francisco, Calif.), presented Apr. 30, 1992, 6 pages in length.
R. F. Wolffenbuttel article, "Photodiodes in Silicon With an Intrinic Colour Filtering Capability," Transducers, from Delft Univ. of Technology, Dept. of Electrical Engineering (1987), pp. 219-222.
R. F. Wolffenbuttel, "Color Filters Integrated with the Detector in Silicon", IEEE Electron Device Letters, vol. EDL-8, No. 1, Jan. 1987, pp. 13-15.
R. F. Wolffenbuttel & G. De Graff, "Performance of an Integrated Silicon Colour Sensor with a Digital Output in Terms of Response to Colours in the Colour Triangle", Sensors and Actuators, A21-A23 (1990), pp. 574-580.
P. L. P. Dillon, A. T. Brault, J. R. Horak, E. Garcia, T. W. Martin & W. A. Light, "Fabrication and Performance of Color Filter Arrays for Solid-State Imagers," IEEE Transactions on Electron Devices, vol. ED-25, No. 2, Feb. 1978, pp. 97-101.
T. Noda, A. Kouno & T. Ando, "An Economical Color-Television Camera Utilizing a Silicon Vidicon for Electronic Color Separation", IEEE Transactions on Electron Devices, vol. ED-22, No. 5, May 1975, pp. 248-251.
Thesis by M. G. Weling, submitted to Univ. of Hawaii, "Amorphous Silicon Color Sensors," dated Dec. 1990, Thesis Committee: V. Malhotra, J. W. Holm-Kennedy, K. Najita.
Davenport T.
Nelms David C.
The University of Hawaii
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